全文获取类型
收费全文 | 73712篇 |
免费 | 3503篇 |
国内免费 | 406篇 |
专业分类
耳鼻咽喉 | 975篇 |
儿科学 | 1944篇 |
妇产科学 | 1672篇 |
基础医学 | 9953篇 |
口腔科学 | 2035篇 |
临床医学 | 5378篇 |
内科学 | 17911篇 |
皮肤病学 | 1685篇 |
神经病学 | 6530篇 |
特种医学 | 2481篇 |
外国民族医学 | 6篇 |
外科学 | 9105篇 |
综合类 | 401篇 |
一般理论 | 20篇 |
预防医学 | 6953篇 |
眼科学 | 1365篇 |
药学 | 5018篇 |
中国医学 | 330篇 |
肿瘤学 | 3859篇 |
出版年
2023年 | 456篇 |
2022年 | 1050篇 |
2021年 | 2125篇 |
2020年 | 1122篇 |
2019年 | 1769篇 |
2018年 | 3595篇 |
2017年 | 2271篇 |
2016年 | 1734篇 |
2015年 | 1870篇 |
2014年 | 2548篇 |
2013年 | 3367篇 |
2012年 | 5000篇 |
2011年 | 5155篇 |
2010年 | 2946篇 |
2009年 | 2533篇 |
2008年 | 4197篇 |
2007年 | 4148篇 |
2006年 | 3916篇 |
2005年 | 3904篇 |
2004年 | 3568篇 |
2003年 | 3280篇 |
2002年 | 3095篇 |
2001年 | 1635篇 |
2000年 | 1700篇 |
1999年 | 1421篇 |
1998年 | 563篇 |
1997年 | 379篇 |
1996年 | 357篇 |
1995年 | 312篇 |
1994年 | 274篇 |
1993年 | 257篇 |
1992年 | 674篇 |
1991年 | 561篇 |
1990年 | 537篇 |
1989年 | 471篇 |
1988年 | 421篇 |
1987年 | 433篇 |
1986年 | 385篇 |
1985年 | 331篇 |
1984年 | 247篇 |
1983年 | 200篇 |
1979年 | 180篇 |
1978年 | 164篇 |
1977年 | 135篇 |
1975年 | 144篇 |
1974年 | 149篇 |
1973年 | 156篇 |
1972年 | 159篇 |
1971年 | 143篇 |
1967年 | 134篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
81.
Nuno Fonseca Filomena Caetano José Santos Filipe Seixo Leonel Bernardino Isabel Silvestre Paula Cardoso Filomena Segurado Lopes Inês 《Revista portuguesa de cardiologia》2004,23(3):365-375
INTRODUCTION: In patients (pts) with atrial fibrillation (AF) of more than 48 hours' duration, electrical cardioversion (ECV) should only be performed after 3 weeks of effective anticoagulation. Transesophageal echocardiography (TEE) allows earlier ECV; however, despite exclusion of thrombi in the atrium and left atrial appendage (LAA), cases of thromboembolism related to ECV have been documented in AF. To define a low-risk group for cardioversion without previous anticoagulation, pts were selected for immediate ECV if no thrombi or dynamic spontaneous echo contrast (auto-contrast) were found after TEE and if LAA velocity was more than 0.25 m/sec. METHODS AND RESULTS: We performed TEE in 31 consecutive pts referred for ECV for AF of more than 48 hours' duration and without previous anticoagulation. After TEE the pts eligible for immediate ECV began anticoagulation with low molecular weight heparin (enoxaparin), subcutaneously in therapeutic doses, together with warfarin immediately before cardioversion. Enoxaparin was continued until an INR of over 2 was reached. Based on the TEE findings, the pts were divided in 2 groups: immediate ECV, group A, 20 pts with a mean age of 62 +/- 13 years, 6 female; and conventional therapy with warfarin before ECV, group B, 11 pts, mean age of 67 +/- 10 years (p < 0.05), 2 female. None of the pts in either group had mitral stenosis or previous episodes of thromboembolism. The mean transverse diameter of the left atrium in the 31 pts was 47 +/- 4.5 mm, without statistically significant differences between the 2 groups. Of the 11 pts in group B, 3 had a thrombus in the LAA, 6 dynamic spontaneous echo contrast and the remainder LAA velocities of less than 0.25 m/sec. ECV was achieved in all the pts, with no complications. Oral anticoagulation was maintained for at least a month. At one month, sinus rhythm was maintained in 75% of group A and 45% of group B (p < 0.01). CONCLUSION: In pts with AF of more than 48 hours' duration and no previous history of thromboembolism, the use of our exclusion criteria during TEE enabled stratification of a low-risk population for immediate ECV, which was accomplished effectively and safely in 2/3 of the pts. This strategy is associated with early symptomatic improvement, and may contribute to maintenance of sinus rhythm after one month, which was significantly better than in the pts who had prolonged therapy with warfarin before ECV, despite the differences found in age and left ventricular function. 相似文献
82.
Miguel Cordeiro Pedro Monteiro Dinis Vieira Francisco Parente Nuno Devesa José Moura Luís Providência 《Revista portuguesa de cardiologia》2004,23(3):399-441
Pulmonary embolism (PE) is an important health problem and often a major clinical challenge, not only because of the low specificity of its clinical manifestations but also because of the increasing number of medical circumstances that are risk factors for this illness and the importance of early identification, since prompt and appropriate treatment can decrease mortality from this disease by about 25%. In recent years research on PE has been extensive, directed mainly at trying to determine and characterize its risk factors, establish new clinical probability algorithms, develop new diagnostic methods and put existing ones into perspective, seek new therapeutic approaches (pharmacological and non-pharmacological), and above all establish protocols that can guide the clinician from the stage of clinical suspicion to measures to prevent recurrence. It was the authors' aim to review the most significant literature on this subject, in order to produce a text that reflects the state of the art concerning PE and that can be used as a guide in the clinical approach to this pathology. 相似文献
83.
Telma T Florêncio Haroldo S Ferreira Jairo C Cavalcante Gabriela R Stux Ana L Sawaya 《European journal of cardiovascular prevention and rehabilitation》2007,14(2):346-348
OBJECTIVE: To test the hypothesis that short stature is associated with abdominal obesity, insulin resistance and lipid profile changes. METHODS: Anthropometric data were collected from 237 women (18-60 years old), residents of a shantytown in Maceió. Biochemical profiles of 60 individuals drawn from this population were determined. RESULTS: Total and low-density lipoprotein (LDL) cholesterol levels and insulin resistance rose with increasing waist : hip circumference ratio, particularly in women. Short, overweight individuals exhibited larger biochemical alterations than overweight individuals of average stature. CONCLUSION: Short stature, when associated with overweight, is a risk factor for increased insulin resistance and alterations in lipid profile. 相似文献
84.
85.
Andrés A Rodriguez Michael D Olson Kevin M Miller 《Ophthalmic surgery, lasers & imaging》2007,38(1):23-26
BACKGROUND AND OBJECTIVES: To determine differences in the amount of work involved in caring for functionally monocular patients who undergo cataract surgery compared with binocularly sighted patients. PATIENTS AND METHODS: This was a retrospective study that included 100 consecutive functionally monocular patients and 100 binocularly sighted control patients matched by age (+/-5 years) and date of surgery ( +/-1 year). Office records were reviewed to determine several measures of office and operating room work effort. RESULTS: There was no difference between groups in preoperative telephone calls (P = .136), postoperative telephone calls (P = .580), preoperative office visits (P = .875), postoperative office visits (P = .601), or the number of times surgery was scheduled (P = 1.00). Monocular patients required more time for surgery (37.4 minutes) than binocular patients (32.4 minutes) (P= .010). CONCLUSIONS: It takes longer to perform cataract surgery on functionally monocular patients than on binocularly sighted patients. 相似文献
86.
M Alvarez R Granados D Mauleón G Rosell M Salas J Sallés N Valls 《Journal of medicinal chemistry》1987,30(7):1186-1193
The synthesis and irreversible alpha-blocking activity in the rat vas deferens of a series of tetra- and diamine disulfides 2-38, structural analogues of benextramine (BHC), are described. All compounds containing a central cystamine moiety displayed an irreversible alpha-adrenergic blockade at concentrations ranging from 10(-4) to 6 X 10(-6)M. Potency was increased in cystamines N,N'-disubstituted with 6-aminohexyl groups, especially when the outer nitrogen atoms bear arylalkyl substituents or are enclosed in a ring. However, N,N,N',N'-tetrasubstituted cystamines were poor blockers. Structural specificity in the outer portion of the tetramine disulfide is low, since many types of substituents gave rise to potent alpha-blockers. Even replacement of the outer amines with nonbasic ethers or amides was observed to maintain irreversible alpha-blockade. 相似文献
87.
88.
OBJECTIVES: Little information is available to incoming students in pediatrics residency programs on the experiences of past residents. The objective of this study was to investigate the pediatrics training programs and determine the professional outcomes of graduating residents between 1990 and 2000 in the Western Interregion. POPULATION AND METHODS: Questionnaires were distributed to the 187 medical students enrolled in pediatrics residency programs between 1990 and 2000 in the six university hospital centers of the Western Interregion. The questions concerned the details of training, the modes of residency positions, and current professional and personal situations. One hundred and sixty-five (88%) individuals responded. RESULTS: Seventy-seven percent of the practicing pediatricians stated that the training they had received during residency was adapted to their current practice. This percentage was higher for hospital staff physicians (82%) than for the physicians in private practice (50%) or those with salaried positions outside the hospital system (58%). One hundred and twenty-four had either completed post-residency training (97) or were doing so (27) at the time of the survey. All but one were professionally active, three quarters of them in hospitals and, of these, most were in the hospitals where they had trained. Eighty-six percent of the practicing pediatricians said they were satisfied with their professional work and 73% said they were satisfied with their personal lives. CONCLUSION: These results support the current reflection on reforming the residency training program in pediatrics, especially with regard to its prolongation and the diversification of the training options to take into account the individual student's professional orientation. 相似文献
89.
P. Moya E. Baixeras I. Barasoain J. M. Rojo E. Ronda M. L. Alonso A. Portol s 《Immunopharmacology and immunotoxicology》1987,9(2):243-256
The “in vivo” effect of Inmunoferon (AM3) on the production of interferon (IFN) and natural killer (NK) activity in young and old mice was studied. Although AM3 is not an IFN inducer by itself, enhancements in the serum IFN levels were produced when drug was associated to Newcastle disease virus or bacterial lipopo-lysaccharides as IFN inducers. This effect appeared to be dependent on the time lapsed between the inducer agent and drug. In addition, a significant stimulating effect on NK cell activity was also produced by AM3 treatments. This effect could be a consequence of a marked IFN induction and/or a modifying effect in prostaglandin synthesis. 相似文献
90.